Thermoplastic adhesive dispensing method and apparatus

ABSTRACT

Hot melt thermoplastic adhesive is predeposited on a carrier strip having front and back release surfaces. The carrier strip is rolled into a coil compressing the thermoplastic hot melt into disks which may later be removed for use. The disks are spaced so that the carrier strip may be deformed to expose a single disk to a planar surface permitting simplified dispensing of the disks.

IDENTIFICATION OF RELATED APPLICATIONS

[0001] This patent application is a continuation of U.S. patentapplication Ser. No. 10/125,012, filed on Apr. 18, 2002, entitled“Thermoplastic Adhesive Dispensing Method and Apparatus,” which is acontinuation of U.S. patent application Ser. No. 09/998,950, filed onNov. 15, 2001, entitled “Thermoplastic Adhesive Dispensing Method andApparatus,” which is in turn a continuation of U.S. patent applicationSer. No. 09/363,200, filed on Jul. 29, 1999, now U.S. Pat. No.6,319,442, entitled “Process of Making a Thermoplastic AdhesiveDispensing Tape,” which is in turn a continuation-in-part of U.S. patentapplication Ser. No. 08/909,189, filed on Aug. 11, 1997, now U.S. Pat.No. 5,935,670, entitled “Thermoplastic Adhesive Dispensing Method andApparatus,” which is in turn based upon U.S. Provisional PatentApplication No. 60/036,896, filed on Feb. 6, 1997, all of which areassigned to the assignee of the present invention.

BACKGROUND OF THE INVENTION

[0002] In the preparation of mass mailings, for example, it is oftendesired to attach a card, such as a credit card or the like, to acarrier document so that the former can be peeled easily from thecarrier document for use by a consumer. One method of making such anattachment uses a pressure-sensitive, thermoplastic adhesive. During theprinting or collating process, a portion of the thermoplastic adhesiveis metered onto the carrier document and the card pressed against thismaterial. The equipment for this process includes a heating containerfor the thermoplastic adhesive and a metering pump that may beelectrically actuated.

[0003] Thermoplastic adhesive can be difficult to work with. Its highmelting temperature and adhesive properties present some risk of burn tountrained operators. The price of the equipment for dispensing thethermoplastic adhesive and positioning and placing the attachments makessuch equipment impractical for low volume mailings.

SUMMARY OF THE INVENTION

[0004] The present invention provides a method and apparatus allowingthermoplastic pressure-sensitive adhesives to be used simply and safelyby those who have low-volume requirements. In the present invention,pressure-sensitive thermoplastic adhesive is pre-metered onto a releasestrip which may be rolled into coil. The size and spacing of the metereddots of thermoplastic adhesive allows one dot to be exposed at a timeacross an anvil plate which may be used to press the dot against a cardor the like. The carrier strip may be advanced between the pressingoperation to bring a new dot into position.

[0005] The spacing of the dots along the strip provides simple methodsof dispensing the dots including the use of a specially constructedcardboard dispenser box or the like or various automated meteringsystems and mechanisms to be described.

[0006] Specifically, the present invention provides a thermoplasticadhesive dispensing tape having a flexible carrier tape extendinglongitudinally and having a transverse width and having opposed firstand second release surfaces. Thermoplastic adhesive dots are arrayedlongitudinally along the first release surface so that the carrier tapemay be curved about an axis to expose a single adhesive dot to anabutting planar surface.

[0007] Thus, it is one object of the invention to provide a simple meansfor dispensing thermal plastic adhesive dots without requiring theexpense or hazard of molten thermoplastic adhesive.

[0008] The second release surface may adhere less strongly to thethermoplastic adhesive dot than does the first release surface.

[0009] Thus, it is another object of the invention to provide athermoplastic adhesive dispensing tape that may be unwound from a coilwith the thermoplastic adhesive dots being retained on the first releasesurface.

[0010] The invention includes a method of manufacturing thethermoplastic adhesive dispensing tape by unrolling the flexible carrierstrip from a first reel to expose the first release surface anddispensing molten thermoplastic adhesive at periodic intervals on theunrolled carrier strip. The carrier strip is then rerolled to compressthe dispensed molten thermoplastic adhesive into flat disks.

[0011] Thus, it is another object of the invention to provide foradhesive disks that approximate the size and area that would be providedby an automatic dispensing equipment directly on the surfaces to beadhered together. The action of adjacent coils of the carrier stripmimics that of a card or other planar surface pressing against a moltenportion of thermoplastic adhesives.

[0012] The rerolling of the flexible carrier strip may be delayed untilthe thermoplastic adhesive has skinned over.

[0013] Thus, it is yet another object of the invention to ensure thatthe thermoplastic adhesive dots are retained by the first releasesurface which receives the thermoplastic adhesive in a molten stateprior to it skinning over and therefore adheres to it more strongly.

[0014] The step of dispensing molten thermoplastic adhesive maysimultaneously dispense at least two separate portions of thermoplasticadhesive at transversely separated locations. The method may include thefurther step of longitudinally slitting the flexible carrier stripbetween separate portions of the thermoplastic adhesive prior torerolling the flexible carrier strip.

[0015] Thus, it is another object of the invention to provide for a highthroughput manufacture of adhesive dots with a single dispensing unitwithout jeopardizing the cooling of the dots as is necessary to allowthem to skin over.

[0016] The invention also includes a dispensing apparatus for thethermoplastic adhesive dispensing tape, including a reel support, forholding the thermoplastic adhesive dispensing tape in coiledconfiguration, and a guide for receiving the carrier tape after adhesivedots have been removed. An anvil surface is positioned between the reeland the guide to receive the thermoplastic adhesive dispensing tape asunreeled from the coil and deform the thermoplastic adhesive dispensingtape to expose a single adhesive dot to a planar surface.

[0017] Thus, it is another object of the invention to provide a rapidapplication technique for the thermoplastic adhesive dots on the tape ofthe present invention. The positioning of the dots so that a single dotmay be exposed to a planar surface allows the dots to be readily appliedto planar surfaces by a proper incrementing of the tape over a correctlysized anvil surface.

[0018] The foregoing and other objects and advantages of the inventionwill appear from the following description. In this description,reference is made to the accompanying drawings which form a part hereofand in which there is shown by way of illustration, a preferredembodiment of the invention. Such embodiment does not necessarilyrepresent the full scope of the invention, however, and reference mustbe made therefore to the claims for interpreting the scope of theinvention.

DESCRIPTION OF THE DRAWINGS

[0019]FIG. 1 is a schematic view of a manufacturing system for thepresent invention showing the dispensing of thermoplasticpressure-sensitive dots onto a carrier strip and the winding of thestrip into coils;

[0020]FIG. 2 is a plan view of a section of a strip of the presentinvention showing the ultimate spacing of the dots when flattened;

[0021]FIG. 3 is a cross section through a coil of FIG. 1 showing thecompression of the dots by adjacent coils of the release strip;

[0022]FIG. 4 is a perspective cut-away view of a container fordispensing the coils of FIG. 1 showing the spacing of the dots whichpermits a single dot to be exposed over an anvil surface for attachmentto a card;

[0023]FIG. 5 is a perspective view of the container of FIG. 4 placed inan automatic tape advancing apparatus to pull the release strip apredetermined amount at the pressing of a palm button;

[0024]FIG. 6 is a simplified fragmentary cross section of asemi-automatic dispensing machine positioned for dispensing an adhesivedot on a carrier sheet prior to dispensing;

[0025]FIG. 7 is a view similar to that of FIG. 6 showing a downwardactivation of the apparatus of FIG. 6 advancing a dot from the carrierstrip over a movable anvil surface to be pressed against the carriersheet; and

[0026]FIG. 8 is a figure similar to that of FIGS. 6 and 7 showing theupward return of the apparatus after dispensing, the return causing atensioning of the used carrier strip in preparation of a second stroke.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0027] Referring to FIG. 1, an adhesive dot manufacturing machine 10provides a back tensioned reel 12 holding a differential release carrierstrip 14. The carrier strip 14 is a paper that has a silicon releasematerial on opposed first and second surfaces 16 and 18 selectivelyapplied so that surface 16 provides less release than surface 18.

[0028] The carrier strip 14 is dispensed from the tensioned reel 12 withsurface 16 facing upward to move beneath a pair of thermoplastic gluemetering nozzles 20 (only one of which is visible in FIG. 1) supplied bya metering pump not shown, to dispense side-by-side glue dots 22 ontosurface 16 as surface 16 moves past nozzle 20. Air jet 24 directed onsurface 16 then cools the glue dots 22 which are also cooled by naturalconvection as the carrier strip 14 moves along.

[0029] A slitting knife 26 divides the carrier strip 14 into multiplestrips, each of which are then wound into coils 30 on take-up reels 28under controlled tensioning. Capstan and idler wheels may also beprovided so that the tension on reels 28 may be controlled independentlyof the tension provided by reel 12.

[0030] Referring now to FIG. 3, the glue dots 22 are initially moundedhigh on the surface 16 of the carrier strip 14, but as they are woundabout the reel 28, each glue dot 22′ is compressed beneath surface 18 ofthe carrier strip 14 of the next succeeding layer of carrier strip 14and the surface 18 of the layer of the carrier strip 14 on which it wasdeposited so as to flatten the glue dots 22′ into circular disks.

[0031] The differential release properties of surfaces 16 and 18, thefact that the glue dots 22 were initially applied in a hot state tosurface 16 causing better adherence, and the fact that there is somecooling and hence “skinning over” of the glue dots 22 prior to thewinding on reel 28, all ensure that the glue dots 22 remain adhered tosurfaces 16 as the coil 30 is unwound.

[0032] Referring now to FIG. 2, the spacing of the glue dots 22′ afterflattening on the carrier strip 14 is such that the glue dots 22′ do notoverlap in the dimension defined by the extent of carrier strip 14. Thisensures that there is a margin 32 in that dimension such that anindividual glue dot 22 may be exposed for adhering to a card or the likewithout the risk of the card picking up multiple glue dots 22. Dots 22and 22′ of a preferred embodiment may be separated by three times theirdiameter.

[0033] Referring now to FIG. 4, the coil 30 may be inserted within adispensing container 34 having generally rectangular configuration withtop, side, and bottom walls 36 and a spanning vertical wall 38. Verticalwall 38 includes a coil support hub 40 extending laterally into thevolume of the container 34 from the vertical wall 38 about which thecoil 30 may be positioned. As positioned, the coil 30 is free to rotatealong a horizontal axis with the outer surfaces of the coil containingthe glue dots 22′ being removed from the inner surfaces of the walls 36.

[0034] A slot 43 at one end of the upper wall 36 allows a portion of thecarrier strip 14 to be threaded from within the container 34 out of theslot 43 and across the upper wall 36 with the glue dots 22′ exposed onthe upper surface of the carrier strip 14. The upper wall 36 provides ananvil surface supporting the carrier strip 14 against pressure when acard 42 or the like is pressed down as indicated by arrow 44 against theupper surface of the carrier strip 14 to receive a glue dot 22′.

[0035] As a result of the earlier removal of the glue dots 22′ on thecarrier strip 14, only a single dot 22′ will be exposed on the uppersurface of the container 34 at a time simplifying this attachmentprocess.

[0036] The portion of the carrier strip 14 previously having its dots22′ removed may be received within a slot 46 in a side wall 36 adjacentto the top wall 36 and then threaded out of a similar slot 48 positionedbelow slot 46 to permit sliding of the carrier strip 14 for thedispensing of additional dots 22 while preventing general looseness ofthe carrier strip 14 such as would promote unwinding of the coil 30unintentionally.

[0037] Referring to FIG. 5, the container 34 may be used for manualdispensing or may be placed within an automatic dispensing system 50.Such a system includes a rigid container sleeve 52, holding the lowerportion of the container 34, and a motor drive unit 54 receiving thecarrier strip 14 after dots have been removed and incrementing the tapeby a predetermined amount with a pressing of a palm sized push button56. With each pressing of the button 56, the motor drive unit 54increments the carrier strip 14 by the interdot spacing so as to exposea single dot 22′ at the top of the container 34.

[0038] Referring now to FIG. 6 in an alternative dispensing method, thecoil 30 may be carried on a semi-automatic affixing tool 58. A footportion 60 of the tool 58 is placed at the top of a carrier sheet 63where an adhesive dot will be placed. A plunger assembly 62 attached toslide up and down with respect to the foot portion 60 and biased upwardwith helical tension springs (not shown) so as to normally be held awayfrom the carrier sheet 63 prior to the dispensing action. Plungerassembly 62 has a handle 64 exposed above the coil 30 and connected to ahanger 66 holding the coil for rotation about hanger 66. A lower portionof the plunger assembly 62 includes a convex elastomeric anvil surface68 flanked by rollers 70. The rollers 70 guide the carrier strip 14downward across the lower surface of the anvil 68 which contacts theinner surface 18 of the carrier strip and up between pinch rollers 72which grasp the portion of the carrier strip 14 after dots have beenremoved.

[0039] Referring now to FIG. 7, the handle 64 may be grasped and presseddownward toward the carrier sheet 63 as indicated by arrow 74. The pinchrollers 72 are mounted to be fixed in height with respect to the footportion 60 and to rotate only in a manner that would pull tape from thecoil 30. Hence, with downward motion of the plunger assembly 62, theanvil 68 moves towards the carrier sheet 63 simultaneously causing theunwinding of carrier strip 14 from the coil 30 such that at the momentthe anvil 68 strikes the carrier sheet 63, a glue dot 22′ is positionedimmediately beneath the anvil 68 to be attached to the carrier sheet 63.

[0040] Referring now to FIG. 8, the handle 64 may be pulled upward aidedby the springs (not shown) between the foot portions 60 and the plungerassembly 62, at which time a ratchet lever (not shown) interconnectingthe plunger assembly 62 and the foot portion 60 causes a partialrotation of the pinch rollers 72 in response to the movement of theplunger assembly 62 with respect to the foot portion 60. This rotationof the pinch rollers 72 advances the carrier strip 14 to remove slackand cause it to remain abutted to the anvil 68 in preparation for a newactuation sequence.

[0041] Thus the tape of the present invention provides a simple methodfor dispensing dots of glue for joining materials together without theneed for complex equipment or exposure to heated thermoplasticmaterials.

[0042] The above description has been that of a preferred embodiment ofthe present invention. It will occur to those that practice the art thatmany modifications may be made without departing from the spirit andscope of the invention. For example, a separate release strip may bewound into the coils of the dots to avoid the need for a carrier striphaving opposed release surfaces. Glue dots having shapes other thandisks may be produced by the appropriate dispensing nozzles. In order toapprise the public of the various embodiments that may fall within thescope of the invention, the following claims are made.

What is claimed is:
 1. An adhesive dispensing tape comprising: aflexible carrier tape having a transverse width defined by first andsecond edges and a longitudinal length; and a row of adhesive segmentsspaced apart along said longitudinal length of said carrier tape, eachof said adhesive segments in said row of adhesive segments beingdisposed between said first and said second edges of said transversewidth of said carrier tape; whereby a portion of said carrier tape maybe transversely flexed to expose a single adhesive segment to anabutting planar surface.
 2. An adhesive dispensing tape as defined inclaim 1, wherein said adhesive segments comprise hot melt adhesivesegments, pressure-sensitive adhesive segments, or combinations thereof.3. An adhesive dispensing tape as defined in claim 1, wherein saidcarrier tape has first and second release surfaces, and wherein saidadhesive segments adhere less strongly to said second release surfacethan they do to said first release surface, whereby said carrier tapemay be unwound from a coil with said adhesive segments being retained onsaid first release surface.
 4. An adhesive dispensing tape as defined inclaim 1, wherein each of said adhesive segments are disposed at a pointthat is centered along said transverse width of said carrier tape,wherein said adhesive segments form a substantially straight line in alongitudinal direction along said carrier tape.
 5. An adhesivedispensing tape as defined in claim 1, wherein said adhesive segmentsare disk-shaped.
 6. An adhesive dispensing tape as defined in claim 1,wherein said adhesive segments are disposed in a single row in alongitudinal direction along said carrier tape.
 7. An adhesivedispensing tape comprising: a flexible carrier tape having a widthdimension extending in a transverse direction and a length dimensionextending in a longitudinal direction; and a series of adhesive segmentsnon-contiguously staggered along said length of said carrier tape in thelongitudinal direction, wherein a portion of said carrier tape may betransversely flexed to expose a single adhesive segment to an abuttingplanar surface.
 8. An adhesive dispensing tape as defined in claim 7,wherein said adhesive segments comprise hot melt adhesive segments,pressure-sensitive adhesive segments, or combinations thereof.
 9. Anadhesive dispensing tape as defined in claim 7, wherein said series ofsaid adhesive segments are substantially linearly disposed on saidcarrier tape along the length of said carrier tape.
 10. An adhesivedispensing tape as defined in claim 7, wherein said width of saidcarrier tape is defined by first and second edges and wherein saidseries of adhesive segments is located along said length of said carriertape between said first and second edges of said width of said carriertape.
 11. An adhesive dispensing tape as defined in claim 7, whereinsaid carrier tape has first and second release surfaces, and whereinsaid adhesive segments adhere less strongly to said second releasesurface than they do to said first release surface, whereby said carriertape may be unwound from a coil with said adhesive segments beingretained on said first release surface.
 12. An adhesive dispensing tapeas defined in claim 11, wherein said adhesive disks have a diametermeasured along said first release surface and are separated in thelongitudinal direction by a margin at least equal to the diameter. 13.An adhesive dispensing tape as defined in claim 11, wherein saidadhesive disks have a diameter measured along said first release surfaceand are separated in the longitudinal direction by a margin at leastthree times the diameter of the circular disks.
 14. An adhesivedispensing tape as defined in claim 7, wherein said adhesive segmentsare each disks having a generally circular configuration.
 15. Anadhesive dispensing tape as defined in claim 7, wherein said adhesivesegments are disposed in a single row in said longitudinal directionalong said carrier tape.
 16. An adhesive dispensing tape comprising: aflexible carrier tape having a transverse width defined by first andsecond edges and a longitudinal length comprising a plurality ofadjoining longitudinal segments extending along the entire longitudinallength of said carrier tape, each of said longitudinal segmentsextending the entire transverse width of said flexible carrier tape; anda plurality of spaced-apart adhesive segments distributed on saidcarrier tape along the longitudinal length of said carrier tape, whereinat least one adhesive segment is disposed within each of saidlongitudinal segments on said carrier tape.
 17. An adhesive dispensingtape as defined in claim 16, wherein said adhesive segments comprise hotmelt adhesive segments, pressure-sensitive adhesive segments, orcombinations thereof.
 18. An adhesive dispensing tape as defined inclaim 16, wherein said adhesive segments are disposed on said carriertape along the longitudinal length of said carrier tape in asubstantially straight line.
 19. An adhesive dispensing tape as definedin claim 16, wherein each of said adhesive segments is disposed withinone of said longitudinal segments at a point between said first andsecond edges of said transverse width of said carrier tape.
 20. Anadhesive dispensing tape as defined in claim 16, wherein said carriertape has first and second release surfaces, and wherein said adhesivesegments adhere less strongly to said second release surface than theydo to said first release surface, whereby said carrier tape may beunwound from a coil with said adhesive segments being retained on saidfirst release surface.
 21. An adhesive dispensing tape as defined inclaim 16, wherein only a single one of said adhesive segments isdisposed within each of said longitudinal segments on said carrier tape.22. An adhesive dispensing tape as defined in claim 16, wherein saidadhesive segments are disposed in a single row in said longitudinaldirection along said carrier tape.